I claim, the ornamental design for an exterior surface configuration of a vehicle lamp, as shown and described.
FIG. 1 is a perspective view of an exterior surface configuration of a vehicle lamp showing my present design;
FIG. 2 is a front view thereof;
FIG. 3 is a left view thereof; and,
FIG. 4 is a top plan view thereof.
The broken line showing of the front edge portion of the Vehicle is included for the purpose of illustrating only and forms no part of the claimed design.